Sheet metal nibbling tool



I. JTYERMISH SHEET METAL NIBBLING TOOL iJply 29, 1958 2 Sheets-Sheet 1 Filed may 7, 1956 I INVENTOR. IS DEL Q. YERMISH l. J. YERMISH SHEET METAL NIBBLING TOOL July 29, 1958 2 Sheets-Sheet 2 Filed May 7, 1956 INVENTOR.

lsRBE Q YER MlsH United rates Patent SHEET METAL NmaLiNG TOOL Israel J. Yermish, Philadelphia, Pa, assignor to Fenway Machine Company, Inc, Philadelphia, Pa., a corporation of Pennsylvania Application May 7, 1956, Serial No. 583,181

, 6 Claims. (Cl. 30-228) This invention relates generally to metal cutting tools and more particularly to an improved construction of portable, hand held sheet metal cutting tools of the nibbler type.

A principal object of the present invention is to provide an improved mounting for the die that coacts with the reciprocating punch of the tool to cut out of the sheet metal a successive series of chips or slugs for slitting the work.

In order to provide for the most eflicient cutting action and in order to prevent premature wear of both the punch and the die, the die opening must conform very closely to the size of the punch. However, the size of the punch may be changed from time to time, depending upon the gauge and hardness of the sheet metal to be cut by the nibbling tool,and/or the die opening may become undesirably enlarged due to wearing of the die and/or punch, in consequence of which a corresponding change in the size of the die opening becomes essential. Accordingly, another important object of the present invention is to provide a die mounting whereby the die may be shifted to vary the size of the die opening to accommodate a change in punch size and/ or take up Wearing of the die and/ or punch.

Still another important object of the present invention is to provide an improved construction of device for stripping the work from the punch, the stripper device being simple in design, rugged in construction and comparatively inexpensive to manufacture.

And still another important object of the present invention is to provide an improved construction of fixed guide for the reciprocable punch, the fixed guide being secured in position in a novel manner, which inherently affords a critical advantage in the construction of that portion of the fixed guide intended to project through the slit cut in the work by the nibbling tool.

Other objects and advantages of the present invention will appear more fully hereinafter, it being understood that the invention consists substantially in the construction, combination, location and relative arrangement of parts, all as described in the accompanying drawings and as finally pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a side elevation, partly sectioned, showing a nibblcr tool constructed in accordance with and embodying the principles of the present invention;

Figures 2 through 5 respectively are enlarged front, side, rear and bottom views of the assembled guide section and die plate, shown detached from the nose section of the nibbler tool;

Figure 6 is a section on line 66 of Figure 3;

Figure 7 is a section on line 7-7 of Figure 5;

Figure 8 is a section on line 88 of Figure 6;

Figure 9 is a fragmentary view similar to Figure 1, showing a modified construction;

Figures 10 through 13 respectively are enlarged front, side, rear and bottom views of the assembled guide section and die plate shown in Figure 9, shown detached from the nose section of the nibblcr tool;

Figure 14 is a section on line 1414 of Figure 11;

Figure 15 is a section on line 1515 of Figure 13; and

Figure 16 is a section on line 16-16 of Figure 14.

Referring to Figures 1 throughv 8, and particularly to Figure 1, the nibbler tool constructed in accordance with and embodying the principles of the present invention is provided with a body designated 10, a head designated 11 that is mounted upon the body 10 in axial extension thereof, and a nose designated 12 that extends laterally from the head 11. Normally the body 10 and head 11 extend horizontally, and the nose 12 depends therefrom.

The body 10 houses an electric motor (not shown) that is supplied with power through the medium of a cable 13, the electric motor being controlled by the operator through finger pressure applied to a switch control lever 14 that is mounted on a handle 15. The body 10 and head 11 are internally provided with means (not shown) for translating the rotary motion of the electric motor into reciprocating motion of a punch generally designated 16, the latter being operatively mounted in the nose 12.

The nose 12 is a cylindrical part that is fitted to the under side of the head 11, being secured to the latter through the medium of a circumferentially extending external flange 17. The opposite sides of the nose 12 are inclined to thereby provide a lower terminal portion that is tapered to a blunt tip, as indicated in Figures 2 and 4.-

This nose 12 is provided with a central through bore that has an upper section designated 18 and a lower communicating section of reduced diameter designated 19.

The punch 16 is made of bar stock that'is uniform and round in transverse cross section, being cut away on diametrically opposite sides to render the lower end portion thereof generally rectangular in transverse cross section. The main body portion of the punch, designated 20, is fitted to a plunger (not shown) that is slidably received by the nose large'diameter bore section 18 while the portion of the punch that is generally rectangular in transverse cross section, designated 21, is slidably received by the nose reduced diameter bore section 19, the broad oppositely facing sides of the punch portion 21 respectively presenting fore and aft of the tool.

For guiding the punch portion 21 that extends beyond the tip of the nose 12, the nibblcr tool is provided with a guide generally designated 22. Referring particularly to Figures 2 through 7, this guide 22 is provided with an upright generally rectangular punch backing part generally designated 23 that terminates at its lower end in a horizontally extending generally rectangular die support part generally designated 24 which extends from the punch backing part and laterally to either side thereof.

A portion of the punch backing part 23 immediately above the die support part 24 is grooved on its opposite sides, as at 2525, to afiord a horizontally extending punch backing portion 26 of reduced thickness. ferring particularly to Figure 6, this intermediate punch backing portion 26 is in turn grooved on its opposite sides, as at 2727, to afford a horizontally extending punch backing portion 28 that is wedge shaped in horizontal transverse cross section. The die support part 24 is provided with a vertically extending bore 29, and the frontal face 30 of the intermediate punch backing portion 26 is located forwardly of the rear wall of the bore 29, whereby the latter extended upwardly above the die support part 24 and into the intermediate punch backing portion 26 undercuts the frontal face 30 aforesaid. The upper portion 31 of the punch backing part 23 is provided with a frontal face 32 that is set back from the 3 frontal face 30 of the intermediate punch backing portion 26. r

The fore part of the upper punch backing portion 31 is provided with apair of lugs 33-33 that extend lat erally therefrom in opposite directions, whereby this fore part is rendered T-shaped in vertical transverse cross section, as best shown in Figures 2 and 4. The aft part of the upper punch backing portion 31 is of somewhat reduced thickness, as best shown in Figures 3 and 4.

Referring particularly to Figure l, the guide 22 is fixedly removably secured to the nose 12 of the nibbler tool by a snug fit of the T-shaped fore part of the upper punch backing portion 31 into a complementary recess formed in the back of the nose 12, projection of a pair of screws 34-34 horizontally forwardly respectively through the lugs 33-33, and threading of these screws 3434 into the wall of the nose 12. Referring to Figure 3 it will be seen that when the guide 22 is mounted in the manner aforesaid, the punch backing part 23 extends beyond the tip of the nose 12 in axial extension thereof and laterally rearwardly of the nose 12 a substantial distance beyond the exterior thereof, whereby the intermediate punch backing portion 26 is interposed between the die support part 24 and the tip of the nose 12. In addition, the frontal face 32 of the upper punch backing portion 31 is set back a short distance from the reduced diameter bore section 19 in the nose 12, the frontal face 30 of the intermediate punch backing portion 26 is disposed immediately to the rear of the punch portion 21, in backing relative thereto, and the bore 29 in the die support part 24 is aligned with the punch portion 21.

Turning to Figure 6 it is observed that seated upon the die support part 24 is a generally rectangular die plate 35 that is provided with a notch 36 that extends from the rear thereof forwardly to provide a pair of rearwardly extending laterally spaced parallel arms 37-37 straddling the intermediate punch backing portion 26. These arms 3737 are spaced apart a distance equal to the width of the punch portion 21 and the thickness of the intermediate punch backing portion 26, as a consequence of which the die plate 35 is secured against lateral shifting movement. The notch 36 of the die plate is of such size that when the plate is secured in position, as best shown in Figures 5, 6 and 7, the three walls of the notch co-operate with the frontal face 30 of the intermediate punch backing portion 26 to form a die opening 38 into which the lower extremity of the punch is adapted to project as it penetrates the sheet material, designated W in Figure l, overlying the die plate. The die opening 38 is of a shape closely corresponding to the cross sectional shape of the lower cutting extremity of the reciprocable punch 16.

As best seen in Figure 7 for securing the die plate 35 against forward displacement with respect to its support under the pressure exerted by the expansion of the slug pushed out of the sheet metal being cut, the fore end of the die support part 24 is provided with a centrally located boss 39 through which there is threaded a set screw 40, one end of which abuts the fore end of the die plate 35. Referring particularly to Figures and 8, the die plate 35 is removably secured to the die support part 24 by projection of a pair of screws 4141 vertically upwardly through the die support part 24 and threading thereof into the die plate 35. The screw accommodating apertures in the die support part, designated 4242, are enlarged sufficiently to afford shifting movement of the screws 4141 fore and aft with the die plate 35 relative to the die support part for varying the size of the die opening 38.

The die opening 38 and the underlying bore 29 in the die support part 24 communicate through an enlarged portion of the notch 36 in the die plate 35 that is formed by a bore 42a which extends from the under surface of the die plate 35 upwardly part way through the'latter. As shown in Figure 6 the diameter of-the bore 42a is greater than the width of the notch 36, the diameter of the bore 29 is greater than the diameter of the bore 42a. The bore 29 is offset forwardly relative to the die opening 38 and the bore 42a, whereby in any adjusted position of the die plate 35 fore and aft relative to the die support part 24, the die opening 38, bore 42a and bore 29 fully register for free ejection of the punched out slugs therethrough.

Return now to Figure 1. Operatively associated with the punch 16 to strip the sheet metal W therefrom upon each upward stroke of the punch is a stripper designated generally by the numeral 43. The stripper device essentially consists of a vertically extending shank 44 that is slidably fitted into the nose 12 and which extends beyond the tip thereof. The lower extremity of the shank 44 carries a foot that is in the form of a horizontally extending block 45 which is recessed on its side proximate the punch portion 21, whereby to form a pair of laterally spaced arms 46-46 that extend rearwardly respectively close up against opposite sides of the punch portion 21 and the intermediate punch backing portion 26. For securing the shank 44 in any axially adjusted position, a set screw 47 is threaded through the wall of the nose 12 to operatively engage the shank 44.

Now referring particularly to Figures 9 through 16, the modified nibbler tool is provided with a nose 50, a punch 51 that is reciprocable in the nose 50, a guide 52 for the portion of the punch 51 that extends beyond the tip of the nose 50, a die plate 53 that is carried by the guide 52, and a stripper 54.

Turning to Figures 11 and 12, it is seen that the punch backing part of the guide 52 is provided With an'upper portion 55, an intermediate portion 56 that is reduced in thickness and a lower portion 57 that is still further reduced in thickness. The upper punch backing portion 55 is provided with the lugs 58-58 that extend laterally therefore in opposite directions and fore and aft the full width of the punch backing part. The intermediate punch backing portion 56 is grooved on opposite sides thereof to provide the wedge shaped punch backing portion 59, best shown in Figure 14.

Referring particularly to Figures 10 through 13, the guide 52 is formed at its lower end with the pair of laterally spaced forwardly projecting coplanar arms 60-60, these arms being formed as integral extensions of the punch backing part and being separated from each other a distance equal to the width of the frontal face of the intermediate punch backing portion 56.

Referring to Figure 14, the die plate 53 is of generally U-shape in plan to provide the pair of rearwardly extending arms 6161 which defines therebetween the notch 62 of a width equal to that of the cutting blade of the punch 51 and the spacing between the die supporting arms 60-60. The rear extremities of the arms 61-61 of the die plate 53 are each downwardly turned to form the lugs 63-63 which respectively engage the rear surfaces of the die supporting arms, the die plate being secured in position by means of screws 64.64 which project upwardly through the die supporting arms 604-60 into threaded engagement with the die plate. The notch 62 of the die plate is of such size that when the plate is secured in position, as best shown in Figures 13, 14 and 15, the three walls of the notch co-operate with the frontal face of the intermediate punch backing portion 56 to form the die opening 65 into which the lower extremity of the punch is adapted to project as it penetrates the sheet material W overlying the die plate, free ejection of the punched out slugs being effected by way of the space 66 between the die support arms 60-60.

The stripper 54 is provided with the shank 67 and the plain foot 68 that is fixed to the lower extremity of the shank 67, the stripper device being adjustably secured in position through the medium of the set screw 69.

In view of the detailed description of the construction and operation of the embodiment of Figures 1 through 8 set forth hereinbefore, it is believed that a further detailed description of the construction and operation of the modified form of the invention is unnecessary for a full understanding of the present invention, and, accordingly, is omitted.

Th punch backing portion 28 of the guide 22 and the punch backing portion 59 of the guide 52 are made wedge shaped in transverse cross section to enable the nibbler tool to turn while slitting the Work along a curved line. Known nibbler tools incorporate this feature, but at the same time are so formed and arranged that they seriously limit the cross sectional area available, which is not desirable because this cross sectional area is critical. It should be apparent that with either of the forms of the present invention disclosed herein above, the punch backing part of the guide may be conveniently extended rearwardly any desired distance to obtain the required cross sectional area.

It will be understood, of course, that the present construction of tool as hereinbefore described is susceptible of various changes and modifications which may be made from time to time without departing from the general principles or real spirit of the present invention, and it is accordingly intended to claim the same broadly, as well as specifically, as indicated by the appended claims.

What is claimed as new and useful is:

1. In a motor operated hand held nibbling tool for slitting sheet material, a reciprocable punch, a fixed guide section for said punch having a punch backing part terminating in a die support part, a die plate carried by said die support part, said die plate being notched to provide a pair of laterally spaced arms defining therebetween all but one side of a die opening, said arms being respectively in engagement with opposite sides of said punch backing part to prevent lateral displacement of the die plate with respect to said punch backing part, said one side of the die opening being defined by the frontal face of the latter, and means for shifting said die plate to thereby vary the size of said die opening and/or take up wear on the die plate including adjustable fixed means carired by said die support part for securing said die plate against displacement forwardly of said punch backing part.

2. In a motor operated hand held nibbling tool for slitting sheet material as defined in claim 1 wherein an area of the die support part underlying the die opening is provided with a discharge opening for punchings communicating with said die opening, said discharge opening being of such increased size that said die opening fully registers therewith in any adjusted position of the die plate.

3. In a motor operated hand held nibbling tool for slitting sheet material as defined in claim 1 wherein the means for securing the die plate in position comprises screw means projected into the die support part and said die plate, one of the latter being provided with enlarged openings for accommodating lateral shifting movement of said screw means relative thereto, and axially adjustable screw means having a terminal portion abutting the frontal edge of the die plate.

4. In a motor operated hand nibbling tool for slitting sheet material, a nose section having a face communicating with an internal nose passage adapted to accommodate a reciprocable punch, said punch reciprocating within said passage and external thereto beyond said nose face, said nose also including an exterior recess extending transverse to the axis of punch reciprocation within said passage, die support means having first and second extensions, said first extension conforming in shape to and fitting closely within said nose recess for rigidly securing said means to said nose, said second extension closely underlying the face of said nose and including a punch backing portion having a planar face in registration with one side of said punch for laterally supporting the portion'of said punch external to said nose during reciprocation, said die support means in the region of said second extension projecting substantially beyond the surface of said nose section in a direction transverse to the direction of said passage, whereby the cross-sectional area of said punch backing portion is made suificiently great to resist fracture due to cantilever stress set-up therein during a nibbling operation.

5. The combination according to claim 4 wherein the planar face of said punch backing portion of said second extension is of a width not exceeding that of the punch side in registration therewith, said punch backing portion being of triangular cross section in a plane normal to the axis of punch reciprocation.

6. The combination according to claim 5 further including a stripping device for guiding the punch and allowing it to be Withdrawn from the material without undue edge deformation of the latter, said stripping device being adjustably fixedly supported by said nose section for shifting movement parallel to the axis of punch reciprocation and including means closely non-engagingly embracing the sides of said punch in non-registration with said punch backing portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,174 Gray Mar. 31, 1942 2,278,311 Gray Mar. 31, 1942 2,535,631 Gray Dec. 26, 1950 2,567,095 Benjamin Sept. 4, 1951 

